The term tadarruʿ is employed in the source’s account of the “Son” appearing in Jesus’ human form. To analyze the claim one must distinguish manifestation, association and literal ontological union rather than treating them as synonyms.
Saying that divine guidance was manifested through a holy messenger is not the same as claiming that the messenger is a constituent part of the divine essence. An extraordinary association does not in itself remove a person’s humanity.
The debate therefore turns on precise predicates. “Appearing,” “being associated with,” and “being united with” imply different propositions. Before an objection can be evaluated, the proposition actually asserted must be identified.